Datensatz

Zusammenfassung

Carbon dioxide removal (CDR) involves capturing CO2 from the atmosphere and storing it for decades to millennia. Alongside deep emissions reductions, CDR is required for meeting the temperature goal of the Paris Agreement (IPCC 2022). However, parties to the agreement do not currently distinguish CDR from emissions reductions in their climate pledges. In this perspective, we argue that this lowers transparency and hinders the assessment of how credible and ambitious mitigation plans are. CDR can come from a range of methods, such as afforestation/reforestation, bioenergy with carbon capture and storage (BECCS), biochar, enhanced weathering, or direct air carbon capture and storage (DACCS) (Smith et al 2024). As progress is made in reducing economy-wide gross emissions, successfully scaling CDR would contribute to balancing residual emissions and reaching net-zero. CDR deployment at scale is also required for potentially achieving net negative emissions in the second half of the 21st century and the (partial) reversal of global warming (IPCC 2022). However, since CDR deployment is currently limited and faces a variety of technological, economic and sustainability constraints when scaling up, emissions must still be reduced as swiftly and deeply as possible (Dooley et al 2022b). Current decisions under the United Nations Framework Convention on Climate Change (UNFCCC) do not explicitly foresee an assessment of how countries plan to scale CDR. Nonetheless, many parties already report removals from forestry in their national inventories and pledge them in their climate targets. A subset of these removals are generally considered to constitute CDR, as they are related to direct human intervention (e.g. afforestation/reforestation) (Friedlingstein et al 2023). Still, even though it is present, CDR is hidden from view: the Nationally Determined Contributions (NDCs) and other submitted documents tend to report and pledge net GHG emissions reductions, where emissions and removals are summed in their respective sectors. The IPCC Task Force on National Greenhouse Gas Inventories is leading a process to provide more guidance on reporting novel CDR activities in inventories. But in addition to this, we argue that there is a strong rationale and urgency for transparent CDR targets and pledges under the UNFCCC. Recent evidence points towards a collective gap in scaling CDR in the short-term, and planning for it in the long-term (Lamb et al 2024). Different definitions of CDR are also highly consequential for benchmarking national progress towards net-zero (Gidden et al 2023). In addition, there are concerns that expectations of future CDR deployment may discourage near-term emissions reductions (McLaren et al 2019, Grant et al 2021), and that some countries already over-depend on CDR in their net-zero plans (Smith et al 2022, Dooley et al 2022a). Specific information on CDR is therefore instrumental for evaluating progress towards the climate objectives of the Paris Agreement. In this article we make three suggestions for how to improve transparency on CDR in climate pledges.